S1 gene sequence analysis of a nephropathogenic strain of avian infectious bronchitis virus in Egypt

Abdel-Moneim, Ahmed S; El-Kady, Magdy F; Ladman, Brian S; Gelb, Jack

Nucleotides identities of Egypt/F/03 with commonly used vaccine strains sequences Figure 3 Nucleotides identities of Egypt/F/03 with commonly used vaccine strains sequences. Dots indicate residues identical to Egypt/F/03. Bold letters denotes codon areas. Shaded letters denote sites of differences. histological lesion, virus neutralization, virus re-isolation from trachea, antigen detection in trachea and/or kidney by immunofluorescent or immunoperoxidase techniques [25] [26] [27] [28] [29] . In this study we used tracheal histological lesion and virus re-isolation as parameters for tracheal protection. Kidney histopathology and antigen detection by IFA were used as indicators of kidney protection. Complete protection is expected upon using closely related vaccine strain as the degree of cross protection among IBV strains generally reflects the similarities between the S proteins [12, 30] . The re-isolation of Egypt/F/03 from the trachea of vaccinated birds and the presence of tracheal and renal microscopic lesions as well as viral antigen in kidneys (by IFA) in H120 vaccinated birds denote lack of complete protection afforded by H120 vaccination.